During their most combative debate moments, Donald Trump turns negative and Hillary Clinton turns inward. Past debates and convention speeches suggest that neither is a formula for success on the big stage. When pressed in debates, Trump increases his use of negative emotion words—“disaster, “terrible”—to launch counterattacks, while Clinton logs a noticeable uptick in “me” words—pronouns like “I,” “my,” “mine,” and “myself”—to mount point-by-point defenses, according to a Bloomberg Politics and Quantified Communications analysis of their two general-election face-offs and combined 20 primary debates.

In every one of his 13 presidential debates to date, Trump has, overall, been more positive than negative. While he portrays politicians as “stupid” and the Iran nuclear deal as “disastrous,” he has spent more time talking about how he will make America “great” again and his plans for the country will be a “tremendous” “success.” But there's a trend: In last Sunday’s debate with Clinton, 25 of every 1,000 words Trump uttered were negative-emotion words, outpacing the first general-election debate (22 per 1,000) and all but one primary debate. His positive language, meanwhile, fell from 33 words per 1,000 to 27 between the primary debates and the most recent general-election debate. Against the self-proclaimed backdrop of a “rigged” election, “phony” sexual-assault accusers, and even the “boring and unfunny” satire of Saturday Night Live, Trump’s negative language looks set to rise even further on Wednesday.

Language researchers use audience focus groups and machine learning to identify thousands of words and phrases with consistently positive or negative connotations. Negative emotion words, for example, range from adjectives (“You ought to be ashamed of yourself,” Trump charged last Sunday) to nouns (Trump’s favorite is “disaster”), and even longer phrases (as when Trump called Clinton “out of control” in their first debate).

Combining the negative and positive categories, Trump was the most emotional of all 16 major Democratic and Republican candidates in primary debates. Twenty of every 1,000 Trump words in primary debates were negative, and 33 positive, compared to a more typical 17 and 30, respectively, for Clinton. In the most recent general election debate, Trump used 52 combined negative and positive emotion words per 1,000, versus 47 for Clinton.

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Wednesday’s closing act could be the moment when Trump, pummeled by plummeting poll numbers, finally crosses over to become more negative than positive. That bodes well for Clinton, who excelled in the first general-election debate in part by actively stoking Trump’s negative language. She threw jab after jab, averaging 20 negative emotion words per 1,000 throughout the debate, and Trump responded with more and more fury, jumping from 18 negative words per 1,000 at the start of that debate to 29 at the end. During the debate, Trump’s election chances in prediction markets fell as his negative language rose.

In last Sunday’s town-hall rematch, Trump survived by joining in the act of putting his opponent on defense. For Clinton, the second debate highlighted a tendency to fall back on her own record when under fire. As in several of her primary debates with Bernie Sanders, she focused more on defending herself with “me” words than on appealing to the country with “we” words.

Clinton used “me” words 4.11 percent of the time in the town hall debate, with her most “me”-heavy moments coming as she jumped into confrontations with Trump. On her e-mail practices, she began with “Everything he just said is absolutely false” before mounting a rebuttal that was 6.11 percent “me” words. On taxes, “Everything you’ve just heard from Donald is not true” launched a stretch of 5.01 percent “me” words.

If Clinton defaults to offering personal rebuttals instead of much-needed aspirational connections with voters, the risk is that self-defense becomes self-defeating. Clinton mastered “we” words in her convention speech, but “me” words were often her refuge in the highest-stakes primary debates. The tighter Clinton’s polling margin against Sanders, the fewer “we” words she used in their face-offs.

Wednesday’s grand finale, the last of 24 presidential debates this cycle, will come down not just to which candidate can land a punch on the other, but also to who can stop hitting themselves.